At 8:1 on a 24 MP photo every drag frame rendered the whole 24 MP frame, and a
Retina fit view (about 2800 px) decoded the original of every photo stepped to.
A new render plan (region::plan, pure and tested) makes the cost follow the
canvas, not the zoom:
- the whole-frame render is canvas-sized and never above the preview source
level, the preview size limit or the texture side (a drag drafts that);
- once the view is zoomed past it (by more than 25 %) the visible window is
rendered, cut from a frame that is at most the photo's own pixels, so beyond
100 % the GPU magnifies it instead of a bigger render being made; this also
ends the duplicated second render above 100 %;
- a window is drafted during a drag and a draft of an older value still draws;
- a user who capped the preview size keeps the whole-frame render at fit;
- no window where the picture on screen isn't the frame's own aspect (an
unsupported raw's embedded JPEG cropped differently, #280).
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Nathaniel LedfordandClaude Sonnet 5.5
3255cda67e